I have more idea's for knitting than I can get down on paper or on to my needles. When I teach creativity in my design classes I work with students on techniques to generate ideas.
These are the two most important words for stimulating creativity.
What if ?
Take an existing garment and ask these questions.
What if I made it longer?
What if I make it a different colour?
What if I used a hand painted yarn?
What if I change the neckline?
What if I use a different yarn than the pattern called for?
What if I changed the silhouette?
What if.......Just keep going and by the time you are done you will have a totally different garment design to knit.